It may not be called that but no one also owns it. Only a queen can wear it, and when her tenure ends, she must give it to the next queen. Even Princess Lilian wasn't allowed to wear it fully as a tiara. although she was the wife of a king, she never was HM Queen of the Belgian. So there are some strict rules about this tiara.

So it is confirmed: the 9 Provinces Tiara was passed on to the new Queen!

She looks very nice with it. I think that it is rather wise to start out with the bandeau only, given the situation in Belgium. The large version will probably come out with royal-royal state visits starting.

It is the Queen's tiara. Princess Lilian was not allowed to wear it on its whole.
The first time we saw the Queen's tiara after the late Queen Astrid was Queen Fabiola on her wedding day.
First time a Queen is wearing the Sash of the Leopold's Order, wonderful Queen wearing her jewels more as Queen Fabiola did.

No, it is not an official crown jewel, as Belgium has none. But with the restriction upon using it, I consider it a semi official crown jewel.

There is no way to know if the 9 provinces can only be worn by queens, it was a gift to Astrid and she wears it in her most famous picture. Having been the most famous/beloved queen in Belgium people didn’t quiet accept when Leopold married for the second time. The tiara must have belonged to Leopold after Astrid’s death otherwise Lilian wouldn’t be able to wear the big diamonds in her gold necklace. She might have simply decided not to wear a piece so associated with Astrid, it could have been Leopold’s decision to give his late wife’s tiara to the new queen (Fabiola) as a wedding gift.

Creating a restriction allowing only queens to wear it would be nice, as would be adding the all the jewelry to the royal trust (forbidding them to be sold or to leave the main line of the BRF).

The Belgium jewelry collection is very petit (ironical since the country’s diamonds are so famous), but maybe the collection will increase in the years to come. Queen Mathilde has the Brabant Laurel Wreath Tiara and now the Nine Provinces Tiara (and queen Fabiola’s diamond brooch). Hopefully she will get the Spanish Wedding Gift Tiara and the Queen Elizabeth's Diamond Bandeau.

There are also some jewelry that we now exist like Queen Fabiola’s diamond daisys, the big aquamarine necklace, the wolfers necklace/tiara, the v-shaped diamond necklace (Queen Fabiola), queen Fabiola’s emerald and diamond leaf brooch and other minor jewelry that we hope will stay in the main line.

The only jewelry that people are sure was sold is the Cartier Diadem, so some people believe that some old jewelry are still with the family (maybe under some kind of embargo – like in the greek situation) this would include the Stockholm Tiara (worn by Astrid and Lilian), the Cartier flower tiara (if Lilian actually bought it, I think she would have sold it..), Lilian’s famous diamond & emerald earings, Queen Astrid emerald necklace/tiara and my personal favorite the big emerald brooch..

Well, with many articles about the Belgium Jewellery in the run up to the Abdication and Inauguration I have to admit I came to the conclusion that the Nine Provinces Tiara would be best served by breaking it into nine pieces and sending one to each province! In other words . . . that is one ugly, mishmash of style and design!

However, leave it to Mathilde to create the perfect stlye to showcase the Base of the tiara to good effect. In fact she did more than that, she made it look elegant. Her smooth up do perfectly complemented the somewhat busy base and turned it into a stunning bandeau! It almost looks like a whole new tiara so, well done Mathilde and I can't wait to see how you play around with the rest of the goodies.

__________________MARG"Words ought to be a little wild, for they are assaults of thoughts on the unthinking." - JM Keynes